April 8, 2001—The Commerce Department’s National Institute of Standards and Technology (NIST) presented on April 5 its analysis of how the World Trade Center (WTC) towers collapsed on September 11, 2001. This is reportedly the most detailed examination of a building failure ever conducted.
“Like most building collapses, these events were the result of a combination of factors,” said Shyam Sunder, lead investigator for the agency’s building and fire safety investigation into the WTC disaster. “While the buildings were able to withstand the initial impact of the aircraft, the resulting fires that spread through the towers weakened support columns and floors that had fireproofing dislodged by the impacts. This eventually led to collapse as the perimeter columns were pulled inward by the sagging floors and buckled.”
NIST has identified a number of future practices and technologies that could have enhanced building performance and life safety capabilities on 9-11 had they been available for implementation. All are being considered for NIST’s upcoming recommendations.
NIST also released drafts of 15 reports from three projects of the investigation: analysis of building and fire codes and practices; occupant behavior, egress and emergency communications; and fire service technologies and guidelines.
Recommendations for improvements to building and fire codes, standards, and practices derived from these and the other five projects in the investigation will be released for public comment in June, along with the draft of the final investigation report and drafts of 27 reports from the remaining five projects.
For more information, including a fact sheet on “Findings on Structural and Life Safety Factors” and computer simulations of Boeing 767 aircraft striking the WTC towers, visit NIST.
